Cytokine storms are an excessive immune response triggered by severe viral infections, such as SARS-CoV2. Toll-like receptor 4 (TLR-4) is a key player in these storms. Secondary and co-infections can exacerbate the immune response, leading to amplified cytokine release and potentially severe disease outcomes. This review aims to evaluate the expression of TLR-4 in fungal and bacterial infections that are associated with and secondary to SARS-CoV2. The study collected specimens from 70 patients admitted to a Baghdad hospital’s ICUs and 35 healthy controls, aged 15-80 years, from June 2022 to April 2023. Re¬al-time RT-PCR was used for infection detection, while conventional methods were used to isolate patho¬genic microorganisms and the Vitec 2 system. The findings of this study suggest that TLR-4 may play a crucial role in secondary and co-infections in individuals with severe SARS-CoV2. The study implies that increased TLR-4 expression might contribute to the development of bacterial secondary and co-infections. When TLR-4 detects bacterial components, it triggers immune responses aimed at eliminating the bacte¬ria. However, an overactive TLR-4 response may lead to an excessive release of cytokines, resulting in a cytokine storm. This excessive immune response can cause tissue damage and exacerbate the severity of SARS-CoV2. Furthermore, the TLR-4 expression may not significantly contribute to the immune response against co-fungal infections with SARS-CoV-2, despite its role in antiviral responses and bacterial defense.
